Spark plug



Nov. 6', 1928.

L.. ROTELLA SPARK PLUG 2 Sheets-Sheet 1 Filed June 10, 1925 w v w 2., ...,...ulmnr q :22S \\\\\ln Nov. 6, 1928.

L. ROTELLA SPARK PLUG 2 SheetSV-Sheet Filed June l0, 1925 Fu; .9 mi

InVerrfv l.. Kom-LA Patented Nov. 6, 1928.

UNITED STATES PATENTOFFICE. 1

Louis BOTELLA, or MONTREAL, QUEBEC, camina.

SPARK PLUG. v

Application led June 10, 1925. Serial No. 36,246.

The invention relates to a spark plug, as described in the present specification and illustrated inthe accompanying drawings that form part of the same.

The invention consists essentially of the novel features of construction pointed out in the claim for novelty following a de-v scription containing e an explanation in detail of an acceptable `form ofthe invention. n

The objects of the invention are to intensify the electric spark in ignition systems; to eliminate the `troubles incident to the failure of' the spark due to accumulations of oil and grease and resulting carbon; to lengthen the life of the plugand thereby save money to the consumer; to minimize the attention required to maintain the sparking points in good condition; to visualize the condition of the electric connections for pro; ducing thelspark and determine the state of individual plugs; to reduce the cost of manufacture of sight plugs, and bring them within the range of standard plugs; to minimize the eiiectof heat generation Within the plug; and generally to provide an efficient, economical Yand'reliable spark plug.

- In the drawings, Figure 1 is anelevational View ofthe preferable form of the plug4 completel Figure 2 is a vertical sectional view of the plug illustrated in Figure 1.

Figure 3 is across sectional view on the line 3 3 in Figure 1.

Figure i is anelevational view of a slight modification of the form illustrated in Figure 1. f

` Figure 5 is a verticalv sectional view of the modified form shown in Figure 4. l

Figure 6v is van elevational view of another modification of the plug showing` a metal cap holding a. transparent cover'for sight apertures. y e y i Figure 7 is a vert-ical sectional view of the Vform showninFigure 6.

Figure 8 is a vertical sectional view of a slight modification ofthe form illustrated in Figures 6 and 7.

Figure 9 is a detail of the porcelain body of the forms shown 'in Figures 6, 7 and 8.Y Figure 10 is a cross sectional view on the line 10-10 in Figure 6. f

Figure 11 is a cross sectional view on the line 11-11 in Figure 6.

Figure 12 is an elevational viewof another form of the plug having the cap screwed to tlu porcelain `body on to a reduced upper en Figure 13 is a vertical sectional viewof the form illustrated in Figure r12. y

Figure 14 is a detail of the porcelain body in the form illustrated inFigures '12 and 13.

Lil-.ze numerals of reference indicate correspondingparts inthe various f1 ures.

Referring to the drawings, in 4igures 1, 2 and 3 the preferable forni of the plug is illustrated and in these figures the shell a and nut are of a conventional form and contain the porcelain body c having a taper-ed lower portion d and tapered upper portion e extending to an enlarged waist portion forming upper and lower shoulders for the gaskets g and h. The conducting rod projects above and below the body c and at thelower ends coacts with the ground connection j from the shell in producing the spark for ignition purposes. i

The gasket isbetween the shell rand the porcelainbody while the nut b screws down onY the gasket g whichr is well known construction.

The taperedupper end e of the porcelain bodv allows ample space between itself and the unut b for the purposes of this constructionv and the translucent hollow cap c occupies a part of this space being inserted in the nut Vand so closely fitting thereinto as yto constitue therewith a unit in the finished plug. f

The ycap 7c has an orifice Z at the upper .end and this oriiice is threaded and a bushingfon introduced in the opaline, amber or other `translucent material centrally at the top 'and forming a part therewith.

They conducting rod a` is threaded and screws into the orifice Z to form the gap o within thehollow gap forntensifying the spark at the yignition gap and 'furnishing a sight spark, which will illuminate the complete upper portion of the plug. The rod n is adjusted to its position by theknurled nut ,'19 and locked .by the customary thumb nut a, from 'which the connection is made to the Coils. Itwill be'seen that the complete cap and nut may be removed from the shell together thereby disclosing the `porcelain body and lower conducting rod, thus taking apart the plug in a moment for cleaning purposes.

In Figures l, and- 5, the only difference from the 'form shown in Figures 1 and `2`is c the cylindrical orin of the upper reduced end 'o1 of thebody s and the mounting o f the translucent hollow cap t on said cylindrical end r as well as turningA the upperend u` of the shell /v over the gasket b on the shouli der g/k otherwise the plug is precisely the upper end portion 111 moulded in cylindrical i f shape and extending upwardly frointhe an# ni'ilar sh'oi'ilder 12, said reduced portion having a bronze threaded bushing 13 centrally embeddedvr therein and having Va threaded orifice 14L `forming 'a rod entrance to the interior of the sightk sparking chan'iberfl,y .which li-'s within the reduced upper portion 11, the wall-of this-chamber having the windowsor apertures 16 as sight openings there.-

' into.A

The threaded conducting rod 2O is formed 'at its fupper end with the `driving slot 21 andfat its lower 'end with the point 22, coacting with the-point 18 within the chamber 15 in creat-` ing 'the sight spark -across'tlie gap 23 between ,the two points.

The rod 2O is screwed into-thebushing 13 and. therethrough intothe 'chamber' 15` to foriir the saidfgap 23aiid at fis upper endreX- tends through the cap 24. rllhe cap 24 isof brass or other nonerustingf metal"1 and isr foi-ined of the disk vtop25hav-ingthe central rodfhole 26 and-v tfliefperipheial downwardly extending flange 27.

The cap 24 rests on theL upper end Vof the porcelain body andcaps the tubular glass covering 2S`glazingthe sightl windows 16;v

The flange 27 lits Vsnugly over the glass Stube 2Sandf centers the latter 'as the rod 20inain' -tains the'cap in a central position, `the annue iai under side of the disk top 2o engages the saidglass `and vbrings i-t into Contact withr the shoulder 1'2 fand'tlush with the periphery of -the middle `portion of the body 10.` The glass i covering-28iior the sight end of the body .10

is.- purposely spacedl all around from the i periphery of the reduced portion 11 thereby providing anair space that will eleininate 4the accumulation and ignition, orexplosive land :inflammable gases incident 'to' the situation of the sight sparking ychamber 15,

l The 'adjusting nut 29 having the'knurled edge face 30 is screwed tightly to theV cap 241oii'the rodg20 and the thumb nut 311s screwed only-said rod-2O against the nut 29 rand holds the-wire connector;`

,"llhefaniular *flange B2 from the body 10 and'thetapering base portion therebelow arer `contained within thefinetal shell 83 and the ground connection 34 projects from the/shell, and coacts with the point. 19 in creating the spark for ignition purposes.

Thesiieiiee is externaiiy threaded aan as customary. in-spark plugs, for the connection with the'engine, and internally threaded at 36,to receive the securing nut 37, which encircles thefiniddle portion y38 of the body 10, thereby `securely holding the porcelain in place and completing the plug.

enginethek gasket 39- is introduced between the porcelain and the shell and the gasket 40 is introduced between the slielllo'ckingnut and the shell,`therefore no tl'iroi'igliy the plug.

` In rFgure 8 a modification of the gases cany escape y plug is f shown, stillliaving feature already described,

namely the space between? the glass and 'the i sight chamber wall, butin this/form of the inventionl the sight chamber wall 41 is a separate piece made ofa suitable insulat ing material with the' apertures 42 looking into the sight vchamber 43 andthe -lunderl nut recess 44'. yThe chamber wall v41rv rests (on the body 45., which is of; greater diameter than the outside measurements of" the sight chamber, thereby vforming the shoulder 46,

on which the tubi'ila-r glass 47 stands, saidk lglass being Hush with the outeredge of-ltlie shoulder gto'leave a space 48'v betweenvthe outer 'surface of thev wallr 41 and "the inner surface oifthe glass 47 for the circulation o'iithe air to avoidy the accumlation'of inflammable gases.` V

The conductin rod 49 is introduced in the 'body 45 and may be permanent therewith oi- The rod 51 screws into and through k"the upper portion othe 'sight chamberlwall 41 'um n it maybe held-'.byrtheinut 50 in the recessl44'` as' :found more desirable.

'lien and is locked by the nut l52 and `thumb nut 53v screwed againsttlie cap-54'flanged at the 'outer v edge '55'to"re ceive the glas's 47,.and

lpierced ycentrally forl therod 51, lthelatter centering said rod to hold the ,glassstea'dy f and. in itsv spacedl position, from;y the sight ychamber wall. f

The rods '49 and51 form the sparkingy gap 56 in the sight' chamber 48 andf the rodf`49 t and vground vwire '57' forml the usual sparkp ing gap for ignition. purposes...

-rllhebody 45 is formedwith'va flange 58 midway :of itsr length and a ktapered lower portion 59 fitting with said flange inthe shell- 60,"the latter being `turned over said flange 58 and aholding flange' 61. Thefgas- `ket 62 is introduced between: the Hanges 58 and 61 and the gasket k'iis introduced. between the'tlanges 58 and theconveying surface G4-ortlie7shell601* f c p `In Figures 12, 13, and 14v a, very ellicient Vform of"thisinvention ifsfsho'wn, wherein the transparent dome 65 of opa'lineor o tl'ier translucent material' "takes the place ofr the Yizo ' and above the flange 69, the cylindrical portion 70 which is reduced to form the threaded nipple 7l screwing into the thread 67 of the dome G5.

The dome 65 screws on to the nipple 71 abuts and engages the fibre washer 72 surrounding said nipple thereby insuring a tight hold for the dome on the porcelain.

The conducting rod 73 is placed centrally in the porcelainbody 68 at the moulding Y and therefore remains permanently there? with and this rod 7 3 projects upwardly into the dome 65 and terminates in the point 74 in the sight chamber 75 and enclosed by said dome. The upper end of the rod 7 3 projects below the porcelain body and terminates in 20`"the sparking extremity 7 G, which with the ground connector 77 `Vfrom the shell 7 8 forms the usual sparking gap 79. t

The connector rod 8O is threaded and screws into and through the bushing 66' and is adjusted with respect to the point 74 to form the sparking gap 8l which is Within the sight chamber.

The lznurled nuts 82 and 83 are mounted on the rod 80 and screw tightly to the bushings 66 and are adapted to hold the connector to the wiring.

The shell 78 is formed with the wrench flats 84- and the reduced screw threaded portion 85 for attaching the plug to the engine head and at its upper end 86 it is turned over the flange 69 of the body 68, the washer 87 and 88 being introduced between the shell and the body flange thus firmly holding the body in place. f

This form of the plug is to be `specially commended as the whole top'of the plug isilluminated and' it is not necessary to watch for a flash as the semi-translucent top lights up and shows very plainly without close investigation whether or not the ignition is in good condition.

In the operation of this spark plug, the ground connection is made by screwing the shell into the cylinder head and the other connections are made to the upper conducting rod, as explained thus the current will flow along thev two rods and in doing so will jump the sight gap making a slight spark and continuing will jump the usual gap between the ground connection and the lower point. This construction considerably intensilies` the spark due to the jumping of the sight cap and insures efficient and visible operation under most conditionsl The upper conducting rod is adjustable as explained consequently by loosening the adjusting nut after loosening the thumb nut the threaded conducting rod can be delicately adjusted by a screw driver to fix the distance of the gap to a nicety.

It may be found desirable to mould the upper conductor rod with the top and permanently determine the sight gap, especially is this applicable in the opaline dome top type, which will of course eliminate the central bushing.

lVhat I claim is In a sparlrplug, a dome of translucent material having a circular bore through the upper wall thereof and a metal llerxedly secured in said bore and having a central threaded orifice therethrough, a threaded sleeve frictionally secured on the lower por- ,tion oli" said dome and extending therefrom and externally threaded, a shell formed to receive said, dome and forming a ground connection, insulating material therein, a lower conductor extending through said insulation into said dome, and a terminal having a conductor rod extending through said metal filler into said dome.

Signed at Montreal, Canada, this 28thA day of May, 1925.

LOUIS BOTELLA. 

